Publishing Company combine LOs together / making courses (ebooks)

The user selected a project. He/she can see all the LOs of the project. Through this function the user can link the Learning Objects together. He/she can make a tree structure from the LO's, which represent a module (more than one LO) and a course.
It's also possible to insert a node which don't assign a LO. In this case he/she give information only about the title of the node.